CN107449932B - Method for measuring rotating speed of aero-engine rotor - Google Patents
Method for measuring rotating speed of aero-engine rotor Download PDFInfo
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- CN107449932B CN107449932B CN201710408142.5A CN201710408142A CN107449932B CN 107449932 B CN107449932 B CN 107449932B CN 201710408142 A CN201710408142 A CN 201710408142A CN 107449932 B CN107449932 B CN 107449932B
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01P—MEASURING LINEAR OR ANGULAR SPEED, ACCELERATION, DECELERATION, OR SHOCK; INDICATING PRESENCE, ABSENCE, OR DIRECTION, OF MOVEMENT
- G01P3/00—Measuring linear or angular speed; Measuring differences of linear or angular speeds
- G01P3/42—Devices characterised by the use of electric or magnetic means
- G01P3/44—Devices characterised by the use of electric or magnetic means for measuring angular speed
- G01P3/46—Devices characterised by the use of electric or magnetic means for measuring angular speed by measuring amplitude of generated current or voltage
- G01P3/465—Devices characterised by the use of electric or magnetic means for measuring angular speed by measuring amplitude of generated current or voltage by using dynamo-electro tachometers or electric generator
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Abstract
The speed measuring motor of the aeroengine speed sensor outputs an alternating voltage signal, the frequency of the alternating voltage signal is in direct proportion to the engine speed, and the rotor speed can be obtained by measuring the frequency or the period of the alternating voltage signal. As the alternating voltage signal output by the aeroengine speed measuring motor rises along with the rotating speed, the voltage change range is from 0.1V to 50V, and the frequency change range is up to 83.3Hz (corresponding to the maximum rotating speed of the aeroengine rotor is 100 percent), the invention provides the method for measuring the rotating speed signal frequency based on the high-speed data acquisition card. Meanwhile, because the rotating speed signal output by the speed measuring motor is not a standard sinusoidal signal and has a certain clutter signal, in order to eliminate the clutter of the signal output by the engine speed measuring motor, the invention also provides a method for carrying out digital filtering processing on the signal.
Description
Technical Field
The invention discloses a method for measuring the rotating speed of an aircraft engine rotor, and belongs to the technical field of measurement.
Background
The aeroengine speed sensor (speed measuring motor) outputs an alternating voltage signal, the frequency of the alternating voltage signal is in direct proportion to the engine speed, and the rotor speed can be obtained by measuring the frequency of the alternating voltage signal. The conventional rotating speed measurement has two basic methods, namely a direct frequency measurement method and a periodic measurement method, and in order to ensure certain measurement speed and measurement accuracy, the direct frequency measurement method is suitable for measuring high-frequency signals, and the periodic measurement method is suitable for measuring low-frequency signals.
1. Direct frequency measurement: the gate is formed by the time base signal to count the detected signal. When the gate width is 1s, the frequency of the detected signal can be directly read out from the counter. It is possible that the count has an error of plus or minus one pulse, so the absolute error of this method is 1Hz (for a gate 1s wide). The relative error of the method is reduced along with the rise of the measured frequency, so the method is suitable for measuring high frequency and is not suitable for measuring low frequency.
2. A cycle measurement method comprises the following steps: and forming a gate by the detected signal, and counting the time base pulse. When the gate width is just one pulse period to be measured, the period value (expressed by the number of time-base pulses) of the signal to be measured can be directly read out from the counter. The absolute error of this method is one time base period. The relative error of the method is reduced along with the increase of the period of the measured signal, so the method is suitable for measuring low frequency (long period) and is not suitable for measuring high frequency (short period).
At present, no matter which method for measuring the rotating speed, as the alternating current voltage signal output by the aeroengine tachometer motor rises along with the rotating speed, the voltage change range is from 0.1V to 50V, and the frequency change range is up to 83.3Hz (corresponding to the maximum rotating speed of an aeroengine rotor is 100%), a signal conditioning circuit is needed to condition the alternating current voltage signal output by the aeroengine tachometer motor into a standard TTL level signal, and when the engine is at a low rotating speed (< 5%), a large error can occur due to the influence of the signal conditioning circuit. In order to solve the problem, the invention provides a method for directly acquiring and analyzing the time domain signal of the rotor rotating speed of the aircraft engine, so that the rotor rotating speed of the aircraft engine can be accurately obtained without time delay.
Disclosure of Invention
The invention provides a method for measuring the rotating speed of an aircraft engine rotor, aiming at the defects in the prior art, the method does not need a signal conditioning circuit, only attenuates the signal by 5-10 times, is equivalent to directly measuring the alternating current signal of a tachometer motor, and can still accurately measure the rotating speed of the rotor of the engine even if the rotating speed of the rotor of the engine is less than 2%.
The method is realized by the following technical scheme:
the method for measuring the rotating speed of the rotor of the aircraft engine comprises the following steps:
step one, constructing a hardware system for measuring the rotating speed of an aircraft engine rotor
The system comprises an attenuator (2) which is 5-10 times connected with a speed measuring motor (1) on the aeroengine, wherein the attenuator (2) which is 5-10 times is connected with an acquisition card (3), the acquisition card (3) requires a sampling rate which is not less than 1MS/s and a sampling resolution which is not less than 16 bits, and data acquired by the acquisition card (3) are transmitted to a computer for processing;
step two, processing the data acquired by the acquisition card (3), wherein the processing process is as follows:
2.1, setting a trigger threshold line (4) for an alternating voltage signal output by the speed measuring motor (1), and enabling the trigger threshold line (4) to be lower than the amplitude of the alternating voltage signal to obtain a rising edge time point (5) when the alternating voltage signal passes through the threshold line;
2.2, calculating the time interval of two adjacent rising edge time points (5), if the time interval is more than 10ms, the time is the period of the rotor speed signal of the aircraft engine, and outputting, displaying and recording the period value;
2.3, calculating the time interval of two adjacent rising edge time points (5), if the time interval is less than 10ms, recording the time values of the front and rear rising edge time points (5) and storing the time values into an array a, continuously searching the next rising edge time point (5) until the time interval between the rising edge time point (5) and the first rising edge time point (5) is more than 10ms, storing the time value of the last rising edge time point (5) into an array b, and averaging the data of the array a to obtain a first rising edge time calculation point t1 for calculating the rotor speed signal period;
2.4, taking the last rising edge time point (5) as the first rising edge time point (5) of the array b, repeating the step 2.3, and averaging the data of the array b to obtain a second rising edge time calculation point t2 for calculating the rotor speed signal period;
and calculating the time interval of the two rising edge time calculation points of t1 and t2, namely the period of the rotor speed signal of the aircraft engine, and outputting, displaying and recording the period value.
The technical scheme of the invention adopts a high-speed acquisition card and a computer to complete time domain signal measurement of the rotor rotating speed. Generally speaking, the signal to be collected determines the requirements of sampling rate and resolution, the current testing technology adopts PCI and PXI (VXI) platforms to conveniently realize the sampling rate of 100MS/s and the sampling resolution of 24 bits, and the acquisition card adopted by the invention can theoretically reach the frequency precision of not less than 0.01 percent and the voltage measurement precision of 0.01 percent only by the sampling rate of not less than 1MS/s and the sampling resolution of not less than 16 bits. The voltage resolution thus analyzed can reach 0.3mv (calculated as the maximum voltage peak-to-peak value after attenuation is ± 10 v), and the frequency resolution can reach 0.01Hz (calculated as the maximum measurement frequency of 100 Hz).
For the collected test data, because the alternating voltage signal output by the speed measuring motor is not a pure sinusoidal signal, an analysis processing method for the test data needs to be considered to filter out interference and clutter. And analyzing the rotating speed signal by setting a trigger threshold line, and calculating the period of the rotating speed signal to obtain the rotating speed of the rotor. The lower limit of the minimum frequency measured by the invention is set at 1Hz, and the upper limit of the maximum frequency is set at 100Hz, thus completely meeting the requirements of practical use. As the difference of the fixed sampling frequency to the sampling points of the signals with different frequencies (1 Hz-100 Hz) in a rotating speed period is 100 times, the invention provides a method for realizing the analysis of the signal frequency by a variable period sampling mode. For signals lower than 1Hz (the minimum frequency lower limit can be set), the voltage amplitude is too low and has no practical significance, the current rotation speed is 0Hz by default, a rotation speed signal is calculated every N cycles at other times (the rotation speed signal frequency is in the range of 1Hz to 100Hz), and the N value can be set to be 1-100 and depends on the requirement degree of a user on the stability and the real-time performance of measured data.
The method for measuring the frequency of the rotating speed signal based on the high-speed data acquisition card is characterized in that the rising edge of the time domain waveform of the rotating speed signal passing through a threshold line is calculated, if the rotating speed signal is a standard sine signal, the time difference between the two rising edges is the rotating speed period to be measured, the rotating speed signal output by the speed measuring motor is not the standard sine signal, a certain clutter signal exists, and in order to eliminate the clutter existing in the signal output by the engine speed measuring motor, the signal needs to be subjected to digital filtering processing. If the measured time domain signal is directly filtered, the data processing amount is too large, and the filtering effect is not good. The invention provides a method for filtering rising edge data of a threshold line and a rotating speed signal, the data participating in filtering is greatly reduced, interference data is filtered according to the condition of the obtained data, because a high-speed parallel acquisition card with the sampling rate not less than 1MHz is adopted for the signals less than 100Hz, the time interval between each sampling point is not more than 1 mu s, invalid data can be basically judged if the time interval between the collected rising edges is less than 10ms, and in order to improve the reliability of the judgment, the algorithm provided by the invention provides that the interference data is filtered by adopting an ultra-amplitude filtering mode, and when the time interval between the rising edges is far less than the expected rotating speed signal period, the average value of the continuous rising edge time points is taken as the rising edge trigger time which needs to participate in calculation actually.
The conventional measurement of the rotating speed of the rotor of the aircraft engine is influenced by a signal conditioning circuit, so that the measurement is often inaccurate for low rotating speed signals (< 5%), the invention basically does not use the signal conditioning circuit, only attenuates the signals by 5-10 times, and is equivalent to directly measuring alternating current signals of a speed measuring motor, and the rotating speed of the rotor of the engine can be accurately measured even if the rotating speed of the rotor of the engine is less than 2%.
When the measurement result is suspected, the reason can not be clearly given, and the alternating current signal of the speed measurement motor can be directly measured by the method, so that the problem of rotating speed measurement can be directly judged.
Drawings
FIG. 1 is a diagram of a single-channel measurement system employing the method of the present invention
FIG. 2 is a diagram of a multi-channel measurement system using the method of the present invention
FIG. 3 is a diagram of a standard AC voltage signal output by a tachometer motor
FIG. 4 is a signal diagram of a standard AC voltage signal output by a tachometer motor with noise added
FIG. 5 is a partial enlarged view of the first set of rising edges in the standard AC voltage signal output by the tachometer motor
FIG. 6 is a partial enlarged view of the second set of rising edges in the standard AC voltage signal output by the tachometer motor
FIG. 7 is a graph showing the voltage variation of 0.3mv detected by the 16-bit resolution acquisition card for + -10 v AC signals
FIG. 8 is a graph of a standard 28Hz sinusoidal signal
FIG. 9 is a signal diagram of FIG. 8 after adding 100mv of noise to the sinusoidal signal
FIG. 10 is a partial enlarged view of the first group of rising edges after adding 100mv of noise to the 28Hz sinusoidal signal
FIG. 11 is a partial enlarged view of the second set of rising edges after adding 100mv of noise to the 28Hz sinusoidal signal
Detailed Description
Referring to attached drawings 1 and 2, the aeroengine rotors are mostly dual rotors, and an alternator on the engine is added, and the rotating speed of the rotors which need to be measured at the same time is generally not more than 3, so that on the basis of a single-channel measuring system, a parallel acquisition card (PCI slot) of 1MS/s adopting 4 channels is designed, and is matched with an existing data acquisition system hardware platform of an engine test bed, and a multi-channel high-speed parallel acquisition card based on a PXI/VXI/LXI platform can be selected. The hardware system for measuring the rotor speed of the aircraft engine comprises an attenuator 2 which is 5-10 times connected with a speed measuring motor 1 on the aircraft engine, wherein the attenuator 2 which is 5-10 times is connected with an acquisition card 3, the acquisition card 3 requires a sampling rate which is not less than 1MS/s and a sampling resolution which is not less than 16 bits, and data acquired by the acquisition card 3 is transmitted to a computer for processing;
in order to accurately measure and analyze the rotation speed signal, the acquisition card needs to select a sampling resolution not lower than 16bit, and it can be seen from fig. 7 that the acquisition card with 16bit resolution is selected, and the voltage change of 0.3mv can be detected for an alternating current signal of +/-10 v.
According to the invention, different sampling periods are set according to different rotor rotating speeds (1-100 Hz), the requirement that the number of samples in each period is not less than 10000 is met, and the time measurement precision of each period can be ensured to reach 0.01%. Because the alternating voltage signal output by the speed measuring motor 1 is not a pure sinusoidal signal, an analysis processing method for the test data needs to be considered to filter interference and clutter, a trigger threshold line is set to analyze a rotating speed signal, a period of the rotating speed is calculated to obtain the rotating speed of the rotor, and referring to the attached drawings 3-6, the step of processing the data collected by the collecting card 3 is as follows:
1, setting a trigger threshold line 4 for an alternating current voltage signal output by a speed measuring motor 1, and enabling the trigger threshold line 4 to be lower than the amplitude of the alternating current voltage signal to obtain a rising edge time point 5 when the alternating current voltage signal passes through the threshold line;
2, calculating the time interval of two adjacent rising edge time points 5, if the time interval is more than 10ms, the time is the period of the rotor speed signal of the aircraft engine, and outputting, displaying and recording the period value;
3, calculating the time interval of two adjacent rising edge time points 5, if the time interval is less than 10ms, recording the time values of the front and rear rising edge time points 5 and storing the time values into an array a, continuously searching the next rising edge time point 5 until the time interval between the rising edge time point 5 and the previous first rising edge time point 5 is more than 10ms, storing the time value of the last rising edge time point 5 into an array b, and averaging the data of the array a to obtain a first rising edge time calculation point t1 for calculating the rotor speed signal period;
4, taking the last rising edge time point 5 as the first rising edge time point 5 of the array b, repeating the step 2.3, and averaging the data of the array b to obtain a second rising edge time calculation point t2 for calculating the rotor speed signal period;
and calculating the time interval of the two rising edge time calculation points of t1 and t2, namely the period of the rotor speed signal of the aircraft engine, and outputting, displaying and recording the period value.
Because of the difference of the rotor rotating speed, the frequency of the rotating speed signal is calculated according to a time domain signal calculation method, each rotating speed period can obtain a rotating speed frequency, for the signal lower than 1Hz (the minimum frequency lower limit can be set), the voltage amplitude is too low and has no practical significance, the rotating speed is 0Hz at the moment by default, a rotating speed signal is calculated every N period at the rest time (the rotating speed signal frequency is in the range of 1 Hz-100 Hz), and the N value can be set to be 1-100 and depends on the requirement degree of a user for the stability and the real-time property of the measured data.
The invention provides a method for measuring the frequency of a rotating speed signal based on a high-speed data acquisition card, which is characterized in that the rising edge of a time domain waveform of the rotating speed signal passing through a threshold line is calculated, if the rotating speed signal is a standard sine signal, the time difference between the two rising edges is the rotating speed period to be measured, the rotating speed signal output by a speed measuring motor is not the standard sine signal and has a certain clutter signal, and in order to eliminate the clutter of the signal output by an engine speed measuring motor, the signal needs to be subjected to digital filtering processing. If the measured time domain signal is directly filtered, the data processing amount is too large, and the filtering effect is not good. The invention provides a method for filtering rising edge data of a threshold line and a rotating speed signal, the data participating in filtering is greatly reduced, interference data is filtered according to the condition of the obtained data, the time interval between each sampling point is not more than 1 mu s because the sampling rate is not less than 1MHz aiming at the signal less than 100Hz, the time interval between the collected rising edges can be judged to be invalid data basically if the time interval is less than 10ms, in order to improve the reliability of the judgment, the algorithm provided by the invention provides that the interference data is filtered by adopting a mode of super-amplitude filtering and average filtering, and when the time interval between the rising edges is far less than the expected rotating speed signal period, the average value of the continuous rising edge time points is taken as the rising edge trigger time which needs to participate in calculation actually.
Referring to fig. 8, 9, 10, and 11, taking a standard 28Hz sinusoidal signal as an example, when a sampling rate of 1MHz is adopted, a threshold line is 1.5V, and a calculated frequency is 28.0002Hz, taking into account that an actually measured signal is not a standard sinusoidal signal but has a certain interference clutter, adding 100mv noise to the standard signal, and calculating an average value of a rising edge group of a first part to be 0.0151315s, that is, a first rising edge time calculation point t1 for calculating a rotor speed signal period obtained by averaging data of an array a; calculating the average value of the rising edge group of the second part as 0.0508575s, namely calculating the second rising edge time calculation point t2 for calculating the rotor speed signal period obtained by averaging the data of the array b; therefore, 1/0.0508575-0.0151315 ≈ 27.9908Hz is obtained, and the frequency measurement accuracy obtained by the algorithm of the invention is still high.
Claims (1)
1. A method for measuring the rotating speed of an aircraft engine rotor is characterized by comprising the following steps: the method comprises the following steps:
step one, constructing a hardware system for measuring the rotating speed of an aircraft engine rotor
The system comprises an attenuator (2) which is 5-10 times connected with a speed measuring motor (1) on the aeroengine, wherein the attenuator (2) which is 5-10 times is connected with an acquisition card (3), the acquisition card (3) requires a sampling rate which is not less than 1MS/s and a sampling resolution which is not less than 16 bits, and data acquired by the acquisition card (3) are transmitted to a computer for processing;
step two, processing the data acquired by the acquisition card (3), wherein the processing process is as follows:
2.1, setting a trigger threshold line (4) for an alternating voltage signal output by the speed measuring motor (1), and enabling the trigger threshold line (4) to be lower than the amplitude of the alternating voltage signal to obtain a rising edge time point (5) when the alternating voltage signal passes through the threshold line;
2.2 calculating the time interval of two adjacent rising edge time points (5), if the time interval is more than 10ms, the time interval is the period of the rotor speed signal of the aircraft engine, and outputting, displaying and recording the period value;
2.3, calculating the time interval of two adjacent rising edge time points (5), if the time interval is less than 10ms, recording the time values of the front and rear rising edge time points (5) and storing the time values into an array a, continuously searching the next rising edge time point (5) until the time interval between the rising edge time point (5) and the first rising edge time point (5) is more than 10ms, storing the time value of the last rising edge time point (5) into an array b, and averaging the data of the array a to obtain a first rising edge time calculation point t1 for calculating the rotor speed signal period;
2.4, taking the last rising edge time point (5) as the first rising edge time point (5) of the array b, repeating the step 2.3, and averaging the data of the array b to obtain a second rising edge time calculation point t2 for calculating the rotor speed signal period;
and calculating the time interval of the two rising edge time calculation points of t1 and t2, namely the period of the rotor speed signal of the aircraft engine, and outputting, displaying and recording the period value.
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| DE102018222791B4 (en) * | 2017-12-22 | 2024-02-01 | Continental Automotive Technologies GmbH | Speed sensor with increased resolution and multiple switching thresholds |
| CN111679091A (en) * | 2020-04-30 | 2020-09-18 | 中国航发南方工业有限公司 | High-real-time segmented self-adaptive rotating speed measuring method, device, medium and equipment |
| CN113110379B (en) * | 2021-03-30 | 2022-04-05 | 西安交通大学 | Speed measurement and time consumption data analysis method for airborne model of aircraft engine |
| CN113202653A (en) * | 2021-05-21 | 2021-08-03 | 成都凯天电子股份有限公司 | Automatic measuring system for engine running data |
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| SU638896A1 (en) * | 1977-07-01 | 1978-12-25 | Уфимский Авиационный Институт Имени Орджоникидзе | Thermoanemometric transducer |
| SU877442A1 (en) * | 1978-07-11 | 1981-10-30 | Предприятие П/Я Г-4903 | Automatic dc electrical thermoanemometer |
| SU964545A2 (en) * | 1979-12-07 | 1982-10-07 | Московский Ордена Ленина Авиационный Институт Им.Серго Орджоникидзе | Air stream direction measuring device |
| SU1448282A1 (en) * | 1986-05-30 | 1988-12-30 | Московский Инженерно-Физический Институт | Apparatus for measuring the speed of movement of models |
| CN101123409A (en) * | 2007-07-17 | 2008-02-13 | 西北工业大学 | Precise rotation speed source device for aviation |
| GB2495104A (en) * | 2011-09-28 | 2013-04-03 | Oxford Rf Sensors Ltd | Rotor blade sensor |
| GB2506424B (en) * | 2012-09-28 | 2017-06-07 | Salunda Ltd | Target clearance measurement device |
| CN104677486B (en) * | 2013-11-27 | 2017-10-24 | 中国航空工业集团公司第六三一研究所 | The aero-engine vibration signal Method for Phase Difference Measurement reconstructed based on tacho-pulse |
| CN105545492A (en) * | 2015-12-10 | 2016-05-04 | 陕西航空电气有限责任公司 | Multi-section acceleration starting control method of aircraft engine |
| CN106404404B (en) * | 2016-08-29 | 2019-02-01 | 中航动力股份有限公司 | Device for testing rotating speed and its test method under a kind of aero-engine operating status |
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